Hello. I have written several chapters of a book, and decided, belatedly, to add a table of contents. I looked through the guide, and discovered, to my delight, that I could do it quite easily simply by selecting text and using the TOC tool to include it. Unfortunately, I quickly discovered that every selection became two entries. I assume this is because each selection consisted of multiple lines, like this:

Chapter 1

I Am Born

In my document the text is centered. These are just text, not headings.

I selected all three of these lines, and told the tool to include them in the TOC. However when I create the TOC I get something like this:

Chapter 1 2
I Am Born 2

What would really like is what you usually see in a TOC, something like:

Chapter 1 I Am Born 2

There should be significant whitespace between the three parts of that(Chapter/Title/Page), but I don't know how to do that in BBCode.

I have tried configuring the style to tell it to replace line breaks with spaces, but this does not seem to have any effect.

You need to use "soft-returns" in your chapter headings to get them to appear as single entries in your TOC.
As for the "significant amount of whitespace" between the two parts , I'm not sure if there is a good solution, especially since you are working with centered titles. Space in the heading does go through, but you will need to add the same amount of space on the other side to balance the heading. Here is a sample: